1. Field of the Invention
The present invention relates to a current sensor to measure the magnitude of current.
2. Description of the Related Art
Current sensors capable of measuring a large current in a contactless manner have recently been demanded. Such current sensors in practical use include a current sensor which measures a current to be measured (hereinafter, referred to as a “target current”) flowing through a current path (hereinafter, referred to as a “target current path”) by detecting a change in magnetic field generated by the target current through a magnetic sensor disposed near the target current path.
This sensor is configured such that multiple long current paths extending in a specific direction are arranged parallel to each other and a magnetic sensor is provided for each current path. Accordingly, the magnetic sensor provided for a target current path may be affected by a magnetic field generated by another current (adjacent current) flowing through a current path (adjacent current path) adjacent to the target current path. Disadvantageously, the accuracy of measurement of a target current may be reduced. To prevent the accuracy of target current measurement from being reduced due to the effect of a magnetic field from an adjacent current path, current sensors recently developed are configured as follows: Each magnetic sensor is positioned such that a magnetic field generated by a target current is oriented along a sensing axis of the magnetic sensor and a magnetic field generated by an adjacent current is orthogonal to the sensing axis (refer to, for example, U.S. Patent Application Publication No. 2009/0121704 and Japanese Unexamined Patent Application Publication No. 2010-019747).
In the above-described current sensors, since each magnetic sensor has to be positioned such that a magnetic field generated by a target current is oriented along the sensing axis and a magnetic field generated by an adjacent current is orthogonal thereto, extremely highly accurate positioning of the magnetic sensor is required. Furthermore, since the magnetic sensor has to be tilted from a direction perpendicular to a main surface of a target current path such that the orientation of the magnetic field generated by the adjacent current is orthogonal to the sensing axis, extremely highly accurate mounting of the magnetic sensor is also required. The above-described current sensors therefore require highly accurate positioning and mounting of the magnetic sensors in order to prevent the accuracy of measurement of a target current from being reduced due to the effect of a magnetic field generated by an adjacent current.